Charging device

ABSTRACT

The invention relates to a charging device ( 1 ), more preferably an exhaust gas turbocharger for a motor vehicle, with a turbine housing ( 3 ) adjoining a bearing housing ( 2 ), in which a variable turbine geometry ( 4 ) is arranged. It is substantial for the invention
         that a one-piece disc spring ( 5 ) of plate with a bent over edge region is provided, wherein the bent over edge region forms a spring leg ( 6 ), while a protective leg ( 7 ) is designed as heat protection for the spring leg ( 6 ),   that the spring leg ( 6 ) on the one hand supports itself on the bearing housing ( 2 ) and on the other hand on the variable turbine geometry ( 4 ), preloading the latter against the turbine housing ( 3 ).

The present invention relates to a charging device, more preferably anexhaust gas turbocharger for a motor vehicle, according to the preambleof claim 1.

In modern motor vehicles, so-called exhaust gas turbochargers withvariable turbine geometries are increasingly employed, wherein the poweroutputs and the response characteristics can be adapted to differentoperating conditions of the combustion engine. The variable turbinegeometries employed here mostly have rotatable guide blades and areusually preloaded by means of a spring device, more preferably by meansof a disc spring, relative to a bearing and/or a turbine housing of thecharging device. Because of the high temperatures when operating thecharging device a decline of the spring force of the disc spring canoccur however, as a result of which the operation of the charging devicecan be impaired.

From EP 1 672 177 A1 a generic exhaust gas turbocharger with a cartridgefor the variable turbine geometry arranged in a turbine housing isknown. Here, the variable turbine geometry is fixed by means of aWoodruff key which is constructed of at least two material layers. Theone material layer is intended to generate the axial preload force whilethe other material layer merely serves as a heat shield for theresilient material layer. The manufacture of such a disc spring howeveris involved and consequently expensive.

The present invention deals with the problem of stating an improvedembodiment for a charging device of the generic type which is morepreferably producible more cost effectively. According to the invention,this problem is solved through the subject of the independent Claim 1.Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of providing a chargingdevice with a variable turbine geometry with a one-piece disc springwith a bent over edge region embodied of plate, wherein the bent overedge region forms a spring leg, while the protective leg of the discspring which compared with the spring leg according to FIG. 1 isradially orientated, is embodied as heat shield for the spring leg.Here, the spring leg on the one hand supports itself on a bearinghousing of the charging device and on the other hand on the variableturbine geometry, preloading the latter against the turbine housing. Itis obviously also conceivable that the disc spring preloads the variableturbine geometry against a guide blade cage or on a cover disc. Throughthe one-piece disc spring embodied of plate, which by means of a laterforming operation receives its bent over edge region, atemperature-insensitive, that is extremely resistant disc spring can becreated which maintains its spring force even under extended, highthermal load. The term “bent over” is to be merely understood purelyexemplarily for different forming methods, so that a flanged-over oroffset edge region can also be included under the invention. The discspring produced in this manner is of a simple construction and shaped bymeans of a simple forming method and consequently producible extremelycost-effectively. In addition, the protective leg of the disc springbrings about protection against excessively high temperatures, as aresult of which the disc spring in turn can be improved with respect toits performance and its lifespan. In contrast with the prior art, thedisc spring according to the invention is not produced of two differentmaterials, but merely of a single material.

With an advantageous further development of the solution according tothe invention the bent over edge region of the disc spring is embodiedinterrupted in circumferential direction and comprises a plurality ofstraps. The interruptions provided in circumferential direction can beproduced simply by means of a suitable stamping method with disc springinitially still flat, wherein the stamped-out straps can simply be bentover in a later forming step. Obviously it is also conceivable as analternative that the bent over edge region is embodied closed incircumferential direction, although this results in higher internalstresses caused by the forming process, the spring force of the discspring according to the invention can however be increased on the whole.Irrespective of whether the bent over edge region in circumferentialdirection is embodied closed or interrupted, both alternatives canhowever be produced simply and thus cost-effectively from a productionpoint of view.

Further important features and advantages of the invention are obtainedfrom the subclaims, from the drawings and from the corresponding figuredescription by means of the drawings. It is to be understood that thefeatures mentioned above and still to be explained in the following arenot only usable in the respective combinations stated but also in othercombinations or by themselves, without leaving the scope of the presentinvention.

Preferred exemplary embodiments of the invention are shown in thedrawings and are explained in more detail in the following description,wherein identical reference characters refer to identical or similar orfunctionally identical components.

Here it shows, in each case schematically,

FIG. 1 a sectional view through a charging device according to theinvention in the region of a variable turbine geometry,

FIGS. 2,3 differently configured disc springs,

FIG. 4 a sectional view through a disc spring according to FIG. 2,

FIG. 5 a view as in FIG. 1, however with another embodiment,

FIGS. 6,7 differently configured disc springs,

FIG. 8 a view as in FIG. 1, however with a further embodiment,

FIGS. 9,10 differently configured disc springs.

According to FIG. 1, a charging device 1 according to the invention,which more preferably can be designed as an exhaust gas turbocharger fora motor vehicle, comprises a turbine housing 3 adjoining a bearinghousing 2, in which a variable turbine geometry 4 is arranged. Accordingto the invention, a one-piece disc spring 5, that is formed of a singlecontinuous material, of plate with an edge region bent over on theoutside is provided, wherein the bent over edge region forms a springleg 6, while the compared with the spring leg 6 radial protective leg 7serves as heat shield for the spring leg 6. Obviously the protective leg7 can also be embodied bent the other way round, that is inside. Here,the spring leg 6 on the one hand supports itself on the bearing housing2 and on the other hand on the variable turbine geometry 4, preloadingthe latter against the turbine housing 3.

In principle the disc spring 5 can have different configurations as isfor example shown according to FIGS. 2 and 3. With the disc spring 5according to FIG. 2 the bent over edge region is closed incircumferential direction, while this bent over edge region according toFIG. 3 is designed interrupted in circumferential direction andcomprises a plurality of straps 8. The term “bent over” obviously is notonly intended to mean a bending method, so that the edge region forexample can also be offset or flanged or folded.

The straps 8 shown according to FIG. 3 are usually stamped out whenstamping out the basic shape of the disc spring 5 and subsequently bentover. In contrast with this, with a disc spring 5 according to FIG. 2,the edge region is bent over completely, when not inconsiderablestresses occur during the forming operation. However, these stresses cansubsequently contribute to an increase in the strength of the discspring 5.

Further considering FIG. 1 it is possible to see that both the springleg 6 as well as the protective leg 7 support themselves on the bearinghousing 2 of the charging device 1 while a blade bearing race 9 of thevariable turbine geometry 4 comprises a suitable contact surface 10,more preferably a radial stage, which the disc spring 5 abuts on theother end.

A particular advantage with the disc spring 5 according to the inventionis that on the one hand it can be produced simply and cost-effectivelyand on the other hand its springy effect is retained in the long termsince the protective leg 7 acts as heat shield for the spring leg 6.Because of this, the temperature in the disc spring 5, more preferablyat the contact point of the disc spring 5 with the blade bearing race 9can be lowered, which increases both its spring force as well as itslifespan. Generally, the disc spring 5 according to the invention can beemployed for both diesel and spark ignition engines.

As on the contact surface 10 of the blade bearing race 9, contactsurfaces 10′ and 10″ can also be provided on the bearing housing 2, onwhich the spring leg 6 and the protective leg 7 rest respectively inorder to achieve a certain sealing effect. Through the preload forcegenerated by means of the disc spring 5 the variable turbine geometry 4is pressed in the direction of the turbine housing 3 and thus held inposition. Obviously a disc spring 5 of this type can generally be alsoemployed for additional fixing purposes with a charging device 1, morepreferably for example for fixing a bearing disc or a variable turbinegeometry.

According to FIGS. 5 and 8, the charging device 1 according to theinvention likewise comprises a turbine housing 3 adjoining the bearinghousing 2, in which the variable turbine geometry 4 is arranged.According to the invention, a one-piece disc spring 5 that is formed ofa single continuous material of plate with an edge region (see FIG. 5)bent over on the inside is provided, which bent over edge region thespring leg 6 adjoins, while the compared with the spring leg 6 radialprotective leg 7 serves as heat shield for the spring leg 6. Here thespring leg 6 supports itself on the bearing housing 2 on the one handand on the variable turbine geometry 4 on the other hand, preloading thelatter against the turbine housing 3.

In principle the disc spring 5 can have different configurations as isshown for example in FIGS. 6 and 7. With the disc spring 5 according toFIG. 6 the bent over edge region is closed in circumferential direction,while this bent over edge region according to FIG. 7 is designedinterrupted in circumferential direction and comprises a plurality ofstraps 8. This applies in the same manner also to the disc springs 5shown according to FIGS. 9 and 10.

Further considering FIG. 5 one can see that both the spring leg 6 aswell as the protective leg 7 support themselves on the blade bearingrace 9 of the charging device 1, specifically in the region of contactsurfaces 10 a and 10 b, which more preferably are embodied in the mannerof a radial stage.

Here, the protective leg 7 of the disc spring 5 generally contacts thebearing housing 2 if a sealing function is desired, but need notnecessarily so if for example no sealing is required.

1. An exhaust gas turbocharger device comprising: a turbine housingadjoining a bearing housing, in which a variable turbine geometry isarranged, such that a one-piece disc spring includes at least one bentover edge region, wherein the bent over edge region forms a spring leg,and a protective leg as heat protection for the spring leg, such thatthe spring leg supports itself on at least one of the bearing housingand on the variable turbine geometry, preloading the latter against atleast one of the turbine housing, a cover disc and a cage.
 2. Theexhaust gas turbocharger device according to claim 1, wherein the bentover edge region is closed in a circumferential direction.
 3. Theexhaust gas turbocharger device according to claim 1, wherein the bentover edge region is interrupted and comprises a plurality of straps in acircumferential direction.
 4. The charging device according to claim 1,wherein the bent over edge region is arranged in at least one of outsideand inside.
 5. The charging device according to claim 1, wherein thebent over edge region is produced through at least one of flanging andfolding.
 6. The charging device according to claim 1, wherein thevariable turbine geometry includes a blade bearing race including acontact surface which the disc spring abuts.
 7. The charging deviceaccording to claim 1, wherein at least one of the spring leg and theprotective leg supports itself on the bearing housing of the chargingdevice.
 8. The charging device according to claim 1, wherein the discspring is a heat shield.
 9. The charging device according to claim 2,wherein the bent over edge region is arranged in at least one of outsideand inside.
 10. The charging device according to claim 2, wherein thebent over edge region is produced through at least one of flanging andfolding.
 11. The charging device according to claim 2, wherein thevariable turbine geometry includes a blade bearing race including acontact surface, having a radial stage which the disc spring abuts. 12.The charging device according to claim 2, wherein at least one of thespring leg and the protective leg supports itself on the bearing housingof the charging device.
 13. The charging device according to claim 2,wherein the disc spring is a heat shield.
 14. The charging deviceaccording to claim 3, wherein the bent over edge region is arranged inat least one of outside and inside.
 15. The charging device according toclaim 3, wherein the bent over edge region is produced through at leastone of flanging and folding.
 16. The charging device according to claim3, wherein the variable turbine geometry includes a blade bearing raceincluding a contact surface, more preferably a radial stage which thedisc spring abuts.
 17. The charging device according to claim 3, whereinat least one of the spring leg and the protective leg supports itself onthe bearing housing of the charging device.
 18. The charging deviceaccording to claim 3, wherein the disc spring is a heat shield.
 19. Thecharging device according to claim 4, wherein the bent over edge regionis produced through at least one of flanging and folding.
 20. Thecharging device according to claim 4, wherein the variable turbinegeometry includes a blade bearing race including a contact surface,having a radial stage which the disc spring abuts.